Event Manager help needed

Overall, the event manager should ‘behave’ more like Meetup or Ning:

The event manager should:

Distinguish between users:
IT Admin – access to WP dashboard, can create events
Event Coordinators – approves attendees, can edit events, can access attendee’s email address
Attendees – registers for events
Have a simple web interface (not the WP dashboard) where NON-ADMINS can access, approve, change events and attendees.
Allow setting ‘reminders’ to send email to registered attendees 48 hours before event
Allow multiple people to be notified by email, not just one; preferably different event types to different email
Create and keep a table/file of all email addresses registered so that coordinators can email them in case of changes and to allow ‘email blasts’ notifying folks of upcoming events
Allow thumbnail graphics on listings for events when there is more than one event on that day.

We would very much like to keep our website as the ‘home’ for all events, and have them populate to our Facebook and Meetup pages, rather than the reverse, so that we have more control, but as it is now, the tools are not doing what we need to do.